WASHINGTON
— Foreign-flagged cruise ships serving US ports must comply with the public accommodations requirements of the Americans With Disabilities Act (ADA).

In a case with important implications for the increasingly popular cruise ship industry, the US Supreme Court Monday ruled 5 to 4 that cruise lines operating in US waters must take reasonable steps to make their ships accessible to all passengers - including those who use wheelchairs and electric scooters.

Cruise industry officials had argued that enforcement of American civil rights laws like the ADA aboard foreign-flagged ships would amount to an extra-territorial application of US law.

The vast majority of cruise ships operating from US ports are registered in other countries - like Panama, Liberia, or the Bahamas - and are thus subject to the regulations and sovereign authority of a foreign nation. In addition, cruise ships must comply with international shipping treaties establishing common standards.

Cruise ship companies register their ships overseas to avoid US taxes and more stringent labor and safety regulations. But they base their ships and businesses within the US and primarily target American consumers. For example, 76 percent of all cruise passengers worldwide are US residents, according to industry estimates.

When Congress passed the ADA, it sought to achieve full participation in American life by disabled individuals. Anyone operating public services and accommodations must make reasonable efforts to permit the "full and equal enjoyment" of those services and accommodations despite an individual's disabilities.

While it is clear that the law applies throughout the US, what was less clear was whether it applies aboard foreign-flagged cruise ships that pick up passengers at a US port, depart for international waters, and then return to a US port.

Two federal appeals courts considered the issue and reached different conclusions. The 11th US Circuit Court of Appeals in Atlanta ruled that the ADA applies to foreign-flagged ships, while the 5th US Circuit Court of Appeals in New Orleans ruled that it does not.

In resolving the split, the Supreme Court said that in the past the high court has required a "clear statement" from Congress whenever such laws are meant to be applied outside US jurisdiction. But Justice Anthony Kennedy, writing for the majority justices, said that lacking such a clear statement they had no doubt that the foreign ships fall within the definitions covered by the ADA.

The required accommodations must be readily achievable and easily accomplished, Justice Kennedy said.

Justice Antonin Scalia disagreed. "I would hold that, since there is no clear statement of coverage, Title III [of the ADA] does not apply to foreign-flag cruise ships," he writes in a dissenting opinion joined by Chief Justice William Rehnquist and Justice Sandra Day O'Connor.

The case, Spector v. Norwegian Cruise Line, stems from a class-action lawsuit filed in 2000 by Douglas Spector and several other NCL passengers. They said they were discriminated against during their cruise vacation because of their disabilities.

According to their suit, they were required to pay higher fares, travel with a nondisabled companion, waive any medical liability, and reside in a limited number of less attractive cabins. In addition, there were no accessible public restrooms on the ship, the suit says.

Norwegian Cruise Line officials say the complaints were limited to facilities on two of their oldest ships. One has already been taken out of service, and the other is set to be decommissioned this summer, they say.

Newer cruise ships generally include an array of structural modifications to make access easier for disabled individuals. NCL officials say its newer ships were constructed as if the ADA did apply.